test_object: add some simple test for callback registration
test_object: add some simple test for callback registration

Change-Id: Iaa5d0361cfc748b6634b25f8b5cb138be2e4d88d
Reviewed-on: http://gerrit.aldebaran.lan:8080/13722
Reviewed-by: mnottale <e3ccf1b6558404e921a21fa09cebb1153b50ec36@aldebaran-robotics.com>
Tested-by: cgestes <ddb78fe00abb42f91254c16a0860e38eb0781789@aldebaran-robotics.com>

bsautron/libqi,aldebaran/libqi,aldebaran/libqi,vbarbaresi/libqi,aldebaran/libqi